1. Technical Field
The present invention relates to a printed circuit board and a method of manufacturing the same.
2. Description of the Related Art
Recently, as a substrate serving as an interposer between the substrate and electronic devices becomes light, thin, short, and small rapidly, a high-density and fine pattern has been required. Various attempts to simplify the existing process together with improvement in technologies have been progressed.
There is an additive method of forming a circuit pattern of a printed circuit board. The additive method is to form the circuit pattern on an insulating layer by a plating scheme. Recently, a semi additive method of more efficiently performing a plating scheme has been used. The semi additive method performs surface treatment on the insulating layer to increase roughness and forms a seed layer, which is a base layer for electroplating, by chemical plating. The circuit pattern is completed by forming the seed layer and then performing the electroplating till a thickness of the circuit pattern reaches a predetermined level.
The existing semi additive method requires a surface roughness treatment process and a thickness of 10,000 Å or more to entirely, uniformly form the seed layer on the substrate. When the thickness of the seed layer is larger, there is a problem in that a lead time of a flash etching process to form the circuit pattern and then remove the seed layer may be long and it is difficult to form a fine pitch.
Therefore, when a sputtering process is applied during a process of forming a metal layer of the printed circuit board, the number of processes is reduced, such that the lead time of the process may be short and costs may be saved correspondingly. Further, the circuit pattern having the fine pitch may be implemented by forming the thin, uniform seed layer.
For this reason, as the substrate is miniaturized and highly integrated, a demand for the sputtering process scheme is more increased than the existing plating scheme. The sputtering process scheme may be formed a thin film at a thin thickness. In this case, the film undergoes the process, and thus most of the film is grown to have a crystal orientation of (111). When the crystal orientation is grown only the specific direction, the thin film has a deflective characteristic in terms of mechanical properties, due to anisotropy of a material.
Meanwhile, Patent Document 1 discloses a manufacturing method of forming the seed layer using the sputtering process, in the method for manufacturing a printed circuit board, but the so formed seed layer has a limitation in terms of the anisotropy of the material physical property. Further, the seed layer may have very strong mechanical physical property in a thickness direction, but have a relatively weak physical property in a lateral direction.    Patent Document 1: Korean Patent Laid-Open Publication No. 2009-0105162